A surface crack on the crankshaft, which should have been detectable during the magnetic particle inspection (MPI) procedures, went undetected during two separate inspections. The crankshaft failed from the extension, in overload, of a fatigue crack initiating from an origin subsurface to the fillet radius between the No. 1 rod journal bearing and the No.2 crankshaft cheek, resulting in the total power loss on the right engine. The pilot attempted to perform a single-engine approach in a manner similar to what he recently practiced while flying a high-performance, military style, single-engine jet trainer. This deviation from flight manual procedures and common single-engine approach practices for multi-engine aircraft resulted in the loss of control and impact with the ground.Findings as to Causes and Contributing Factors A surface crack on the crankshaft, which should have been detectable during the magnetic particle inspection (MPI) procedures, went undetected during two separate inspections. The crankshaft failed from the extension, in overload, of a fatigue crack initiating from an origin subsurface to the fillet radius between the No. 1 rod journal bearing and the No.2 crankshaft cheek, resulting in the total power loss on the right engine. The pilot attempted to perform a single-engine approach in a manner similar to what he recently practiced while flying a high-performance, military style, single-engine jet trainer. This deviation from flight manual procedures and common single-engine approach practices for multi-engine aircraft resulted in the loss of control and impact with the ground. The person responsible for maintenance (PRM), who did not have Level2 non-destructive testing (NDT) certification, conducted the propeller strike MPI without supervision.Finding as to Risk The person responsible for maintenance (PRM), who did not have Level2 non-destructive testing (NDT) certification, conducted the propeller strike MPI without supervision. The overhaul facility conducted an internal quality assurance review of its non-destructive testing (NDT) procedures, techniques, and equipment to ensure compliance with existing standards.Safety Action Taken The overhaul facility conducted an internal quality assurance review of its non-destructive testing (NDT) procedures, techniques, and equipment to ensure compliance with existing standards.